Synthesize,Characterization, and Corrosion Inhibition of Polypyrrole Thin Films on Copper

Polypyrrole (PPy) coatings were synthesized on copper by electrochemical polymerization of pyrrole monomer in aqueous acidic and basic solutions by cyclic voltammetry. The coatings were characterized with CV, UV-visible absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) techniques. The corrosion protection aspects of PPy coatings have been investigated using the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The potentiodynamic polarization measurements show that the PPy coating has ability to protect the copper against corrosion. It was concluded that a complete corrosion protective PPy film could not be obtained through direct electro-oxidation procedure. This may be due to copper dissolution in the monomer oxidation potential range.     

An Electrochemical Study on the Corrosion Inhibition of Stainless Steel by Polyaniline Film

Polyaniline(PANI)film was electrosynthesized on 304 stainless steel by cyclic voltammetry using aqueous oxalic acid as supporting electrolyte.The potential sweep rates were changed to achieve the PANI film with different thickness and structures.Protective properties of the PANI film for corrosion of stainless steel in 3% NaC1 aqueous solution were investigated by monitoring potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS).The results showed that the PANI film which was formed with lower sweep rate led to more positive shift of corrosion potential and greater charge transfer resistance,reflecting higher inhibition for corrosion of the stainless steel.     

Electrochemical corrosion resistance performance of sustainable resource-based nanoconducting polymer composites in alkaline medium

The corrosion resistance performance of poly (otoluidine) (POT)-dispersed castor oil-polyurethane, (COPU) nanocomposite coatings, POT/COPU, with three different compositions (i.e. 0.25, 0.5 and 1.0 wt%) in alkaline medium is studied. The coatings are applied on mild steel specimens by brushing. Corrosion resistance behaviour of these coatings is investigated using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS) and by weight loss. The morphological behaviour of corroded and uncorroded coated specimens is investigated by scanning electron microscopy (SEM). It is interesting to report that the presence of conducting polymer nanoparticles in POT/COPU coatings suppresses the saponification of COPU in an alkaline environment. These investigations show that the dispersion of POT in COPU remarkably improves the corrosion resistance performance of COPU in alkaline media. POT/COPU (1.0 wt%) coatings have potential as anticorrosive-coating materials in alkaline media at higher pH. These coatings have a higher resistance to alkaline medium in comparison to other compositions.     

Corrosion resistance of amorphous AlPO4 coating in salty atmospheres

The objective of the present study was to introduce a cost-effective and environmentally friendly coating to improve the corrosion resistance of the structures located in salt water. The coating solution, based on amorphous aluminum phosphate composition, was synthesized by sol–gel process and applied to AISI 304 stainless steel by dip coating technique. X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy analyses were employed to investigate the phase composition and morphology of the coating. Corrosion behavior of the uncoated and coated samples was investigated using standard salt spray test, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. Salt spray test results for the bare substrate revealed a corrosion rate of six-time greater than that of the coated surface after 168 hr exposure time. Electrochemical test results declared that the amorphous AlPO₄ coating decreased the corrosion current density of the AISI 304 stainless steel by 10 orders of magnitude. Furthermore, according to the corresponding EIS measurements, the coated surface exhibited a superior anti-corrosion performance than uncoated sample. Overall, the results declared that the amorphous AlPO₄ coating could be a good choice for surface protection of stainless steel against electrochemical corrosion in salty environments.     

Poly(3-octylthiophene) and polystyrene blends thermally treated as coatings for corrosion protection of stainless steel 304

The effect of thermal annealing of poly(3-octylthiophene) (P3OT) and polystyrene (PS) blend coatings on the corrosion inhibition of stainless steel in a 0.5 M NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride (FeCl₃) as oxidant. Stainless steel electrodes with mirror finish were coated with P3OT/PS blend by drop-casting technique. In order to study the temperature effect on the function like physical barrier against the corrosive species of P3OT/PS polymeric blend, the coatings were thermally annealed at three different temperatures (55?°C, 80?°C, and 100?°C). The corrosion behavior of P3OT/PS-coated stainless steel was investigated in 0.5 M NaCl at room temperature, by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy. The LPR values indicated that, at 100?°C, P3OT/PS coatings showed a better protection of the 304 stainless steel in 0.5 M NaCl; the corrosion rate diminished in two orders of magnitude with regard to the bare stainless steel. The superficial morphology of the coatings before and after the corrosive environment was researched by atomic force microscopy, optic microscopy, and scanning electronic microscopy. Morphological study showed that the increased temperature benefited the integration of the two polymeric phases, which improved the barrier properties of the coatings. The coating/metal adhesion and the coating thickness were evaluated. The temperature increases the adhesion degree coating/substrate; thus, the coating annealed at 100?°C showed the best adhesion.     

Effect of thermal annealing of poly(3-octylthiophene) films covered stainless steel on corrosion properties

The effect of thermal annealing of poly(3-octylthiophene) (P3OT) coatings on the corrosion inhibition of stainless steel in an NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride (FeCl₃) as oxidant. P3OT films were deposited by drop-casting technique onto 304 stainless steel electrode (304SS). 304SS coated with P3OT films were thermally annealed during 30 h at different temperatures (55°C, 80°C, and 100°C). The corrosion resistance of stainless steel coated with P3OT in 0.5 M NaCl aqueous solution at room temperature was investigated by using potentiodynamic polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. The results indicated that the thermal treatment at 80°C and 100°C of P3OT films improved the corrosion resistance of the stainless steel in NaCl solution; the speed of corrosion diminished in an order of magnitude with regard to the 304SS. In order to study the temperature effect in the morphology of the coatings before and after the corrosive environment and correlate it with corrosion protection, atomic force microscopy and scanning electron microscopy were used. Morphological study showed that when the films are heated, the grain size increased and a denser surface was obtained, which benefited the barrier properties of the film.     

A zirconia-polyester glycol coating on differently pretreated AISI 316L stainless steel: corrosion behavior in chloride solution

The effect of zirconia and zirconia-polyester glycol hybrid coatings on the corrosion resistance of mechanically polished or anodized AISI 316 stainless steel (316L), was studied by potentiodynamic polarization and electrochemical impedance spectroscopy in 0.1 M NaCl and scanning electron microscope and atomic force microscopy examinations. The deposition of zirconia coatings was achieved by the sol–gel technique by immersing the samples in either the inorganic polymer or the organic–inorganic polymer mixture. From potentiodynamic and impedance measurements, the grade of protection is reduced with the exposure time to the electrolyte, which is mainly associated with lost of film adhesion and, consequently, detachment from the metal substrate. However, the uncoated anodized sample revealed an unexpected corrosion behavior; the anodic film formed during anodizing readily increased the corrosion resistance of the 316L stainless steel in 0.1 M NaCl, revealing a considerable reduction in the corrosion current density and an increase in the pitting potential.     

Corrosion protection performance of ceria‐copolymer bilayer coating on low nickel stainless steel in 0.5 M H2SO4 medium

In this paper, we have reported the anti‐corrosion performance of ceria / poly (indole‐co‐pyrrole) (Ce/(poly(In‐co‐Py)) bilayer coating on low nickel stainless steel (LN SS). Electrochemical polymerization of (poly (In‐co‐Py)) was achieved on ceria‐coated LN SS (CeO₂/LN SS) in acetonitrile medium containing LiClO₄ (ACN‐LiClO₄) by cyclic voltammetric technique. The coatings were characterized by analytical techniques like Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive analysis of X‐ray, respectively. The mechanical behavior of the coatings was studied using peel test, hardness and wear resistance tests. The corrosion defensive performance of this bilayer coating on LN SS was investigated using electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy in 0.5 M H₂SO₄. These results show that the bilayer coating on LN SS lowered the permeability of corrosive ions present in the acidic medium and thus acts as a barrier against the attack of corrosive environment. Copyright © 2012 John Wiley & Sons, Ltd.     

基于电化学噪声研究模拟海洋大气环境下304不锈钢的点蚀行为

基于电化学噪声技术建立了不锈钢海洋大气点蚀监测系统,利用该系统对处于干湿循环环境下不锈钢的点蚀行为进行监测. 使用时域谱图、时域统计、频域谱图和散粒噪声理论等分析方法对采集到的电化学噪声数据进行处理分析,并结合动电位极化法,形貌分析法共同研究不锈钢的点蚀行为. 研究结果表明,304不锈钢在模拟海洋大气环境下的点蚀行为分为钝化、亚稳态点蚀和稳态点蚀三个阶段. 在钝化阶段,电位电流噪声信号出现少量的同步异向波动,腐蚀事件发生频率高,平均电量低;在亚稳态点蚀阶段,电位电流噪声信号出现大量的同步同向波动,腐蚀事件发生频率降低,平均电量上升,通过扫描电镜观察蚀点;在稳态点蚀阶段,电位电流噪声信号不仅存在大量的同步同向波动,还出现了同步异向波动,腐蚀事件发生频率较低,平均电量大幅度上升,通过扫描电镜观察到电极表面出现小而浅的蚀点. 而动电位极化法可以证实304不锈钢点蚀的发生. 两种分析方法所得结果具有较好的一致性,证明该监测系统很好地实现了对模拟海洋大气环境下304不锈钢点蚀行为的连续监测,并能判断点蚀的发生.     

The electrochemical synthesis of poly(o-phenylenediamine) on stainless steel and its corrosion protection ability in 3.5 % NaCl solution

In this study, electrochemical synthesis of poly(o-phenylenediamine) (PoPDA) on 316L stainless steel and its corrosion inhibition effect were studied. Electropolymerization of o-phenylenediamine (oPDA) was carried out by a potentiodynamic method using 0.5 M H₂SO₄ solution containing 0.05 M oPDA monomer. The corrosion protection ability of the PoPDA in 3.5 % NaCl was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, and change of open circuit potential with immersion time (E_OCP ? t). The results showed that PoPDA acted as a protective layer on stainless steel against corrosion in 3.5 % NaCl solution.     

Two layered silica protective film made by a spray-and-dip coating method on 304 stainless steel

The silica coating has attracted much attention because of its superior corrosion resistance with almost no harm to human health and to the environment. In this study, a two layered silica film was tried to get an enhanced corrosion resistance. The silica film was prepared on the hairline finish 304 stainless steel surfaces by-a-spray- and subsequent-dip-coating process. The spray coating solution was prepared by mixing sodium silicate solution, silica colloid, tetraethyl orthosilicate (TEOS), methyltriethoxysilane (MTES), ethanol, and distilled water. Then the solution was sprayed onto the stainless steel surface, and was dried and heat treated. The dip coating solution was prepared by a simple mixing of TEOS and acidic water into ethanol, and the prior spray coated sample was dipped into the solution. The outer dip coated layer was intended to cover spray coated rough and porous layer and hence to enhance the corrosion resistance. A homogeneous and crack free surface was successfully obtained after the dip coating. The prepared silica film was characterized using scanning electron microscopy, potentiodynamic polarization scan, and electrochemical impedance spectroscopy. The two layered film showed an enhanced corrosion resistance. The enhancement was attributed to a protecting effect of the dip coated layer where the diffusion of ionic species was successfully impeded.     

Electrochemical behavior of Ni-Al-Fe alloys in simulated human body solution

An investigation about the corrosion resistance of Ni-Al-Fe intermetallic alloys in simulated human body fluid environments has been carried out using electrochemical techniques. Tested alloys included 57 (wt%) Ni-(20 to 30) Al-(12 to 23) Fe using the Hank's solution because the high corrosion resistance provided by protective Al₂O₃ external layer. For comparison, AISI 316L type stainless steel has also been used. Electrochemical techniques included potentiodynamic polarization curves, electrochemical impedance spectroscopy, and electrochemical noise measurements. The different techniques have shown that these alloys showed a similar or higher corrosion resistance than conventional AISI 316L type stainless steel, and this corrosion resistance decreased as the Al content in the alloy increased. The alloys were susceptible to pitting type of corrosion on the interdendritic Ni-rich phases.     

EIS study on the corrosion performance of a Cr(III)-based conversion coating on zinc galvanized steel for the automotive industry

The corrosion performance of a new industrial Cr(III)-based conversion coating on zinc galvanized FeP04 steel for the automotive industry was studied. For comparison, the zinc galvanized steel submitted to a Cr(VI)-based passivation treatment was also examined. The corrosion behavior was assessed by means of potentiodynamic polarization and electrochemical impedance spectroscopy measurements in aerated 0.1 M NaCl solution. The behavior of untreated zinc galvanized FeP04 steel in aerated 0.1 M NaCl solution was also studied. The results obtained indicate that with the same thickness, the coating generated in the Cr(III) treatment bath exhibits better corrosion properties compared to the coating formed in the Cr(VI) treatment bath. The difference in the corrosion protection given by the two conversion coating types can be ascribed to the difference in the chromium content and coating composition.     

Sol-Gel Deposition of ZrO2 Films in Air and in Oxygen-Free Atmospheres for Chemical Protection of 304 Stainless Steel: A Comparative Corrosion Study

ZrO₂ coatings for corrosion protection were deposited on 304 stainless steel by sol-gel method using zirconium propoxide as precursor and densified in air and in oxygen-free (argon or nitrogen) atmospheres. XRD and IR data of the films were practically independent of the atmosphere used in the densification step showing that the ceramic oxide is properly formed from the precursor. The corrosion behavior of the stainless steel substrate was studied by potentiodynamic polarization curves in the absence and the presence of ZrO₂ coatings prepared in air, argon or nitrogen. The coatings extended the lifetime of the material by a factor of almost eight in a very aggressive environment, independently of the preparation procedure. The possibility of depositing pure or mixed oxide films by sol-gel methods in the absence of additional oxygen will allow the preparation of specific coatings onto oxygen-reactive substrates.     

碳钢低压冷喷涂铝涂层的海水耐蚀性

本文以Al和10%体积比Al2O3的混合粉末为原料,使用便携式低压冷喷涂设备,在Q235碳钢基体上喷涂了Al涂层. 测试涂层自腐蚀电位及动电位极化曲线,结合扫描电镜观察涂层表面及截面微观形貌,研究了低压冷喷涂Al涂层在海水中电化学腐蚀行为,并与高压冷喷涂和热喷涂铝涂层的耐蚀性比较. 结果表明,低压冷喷涂铝涂层结构较为致密,其耐蚀性比高压冷喷涂铝涂层的略低,而明显优于热喷涂铝涂层.     

Structural and electrochemical characterization of sputter-deposited nitrided NiCr alloys

Nickel-based coatings are potential candidates for the protection of electrochemical dissolution of steel surfaces. Such coatings, elaborated by magnetron sputtering in a nitrogen atmosphere, offer good corrosion protection, good adherence as well as stability for metallic structures. NiCr alloys with almost constant composition have been deposited with different nitrogen contents on stainless steel and carbon steel surfaces. The coating uniformity, homogeneity, composition and crystallinity have been studied by scanning electron microscopy, energy-dispersive X-ray spectrometry, atomic force microscopy and X-ray diffraction techniques. The corrosion degradation behavior of all the samples was tested in NaCl and NaCl and CO₂ mixture exposures using electrochemical impedance spectroscopy measurements. Nitrided NiCr alloys on a stainless steel substrate resulted with better adhesion than carbon steel, by delaying the corrosion mechanism when exposed to NaCl and CO₂ solution. A comparison of the corrosion resistive behavior of the substrates (stainless steel, carbon steel) and the coatings is made by using the electrical capacitance concept from a double-layer model for the coating–metal interface.     

Inhibition effect of hexadecyl pyridinium bromide on the corrosion behavior of some austenitic stainless steels in H2SO4 solutions

The inhibition effect of hexadecyl pyridinium bromide (HDPB) as a cationic surfactant on the corrosion behavior of some Egyptian austenitic stainless steel SS 304L, SS 316H and SS 304H in 0.5 M H₂SO₄ solutions was investigated by using potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The results indicate that HDPB is a good inhibitor for the samples under investigation in 0.5 M H₂SO₄ solutions. In addition, the inhibition efficiency η% increases with the inhibitor concentration while decreases with the increasing temperature referring to physical adsorption. The adsorption of the inhibitor obeys a Temkin adsorption isotherm. Polarization curves show that HDPB is a mixed inhibitor in H₂SO₄ solutions. The results obtained from polarization and impedance measurements are in good agreement. Activation-free energies, enthalpies, and entropies for the inhibition process of HDPB were determined.     

Electropolymerization,characterization and corrosion protection evolution of poly(4-aminomethyl-5-hydroxymethyl-2-methylpyridine-3-ol) on steel and copper

The electrochemical synthesis of poly(4-aminomethyl-5-hydroxymethyl-2-methyl pyridine-3-ol) on steel and copper electrodes was achieved in both sulfuric acid and oxalic acid by cyclic voltammetry technique. Characterization of the polymer films were achieved by Fourier transforms infrared spectroscopy technique (FTIR) and scanning electron microscope (SEM). Corrosion performance of coatings was investigated in 0.1 M H₂SO₄ by potentiodynamic polarization and electrochemical impedance (EIS) spectroscopy techniques.     

Inhibition effect of butan-1-ol on the corrosion behavior of austenitic stainless steel (Type 304) in dilute sulfuric acid

The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance.     

Electrochemical behavior of polypyrrole-coated AZ31 alloy modified by fluoride anions

The electrochemical polymerization of polypyrrole (Ppy) films on AZ31Mg alloys was carried out using cyclic voltammetery in 0.5 M sodium salicylate solution containing 0.25 M pyrrole and different concentration of sodium fluoride (NaF). Corrosion performance of the Ppy film was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5 % NaCl solution. It was observed that Ppy coatings doped in the presence of 100 ppm NaF provide the best corrosion protection for magnesium and the corrosion potential shifted about 290 mV toward nobler potentials and decrease the corrosion current density about one order of magnitude. The surface analysis of the coatings showed that the addition of F^? dopant anions led to an improvement in the smoothness, thickness, and adhesion quality of the synthesized Ppy coating on the Mg surface. The scanning electron microscopy (SEM) studies of the fluoride-doped Ppy films revealed that the synthesized coating has a closely packed globular structure which was composed of nanoparticles of Ppy.